Centrifuge for separating solids from liquid



Sept. 22, 1970 F,W.KEITH,JR., ETAL 3,529,767

' CENTRIFUGE FOR SEPARATING SOLIDS'FROM LIQUID Original Filed Feb. 21962 5 Sheets-Sheet 1 INVENTORS- FREDERICK w KEITH JR ANDRE c. LAVANCHYBY ATTORNEY F. W. KEITH. JR., ETA!- 3,529,767 CENTRIFUGE FOR SEPARATINGSOLIDS mom LIQUID Sept. 22, 1970 Original Filed Feb. 28; 1962 5Sheets-Sheet 3 INVENTORE. FREDERICK W. KEITH,JR. Y ANDRE C. LAVANCHYATTORNEY Sept. 22, 1970 F. w. KEITH, JR., ErAL 3,529,767

CENTRIFUGE FOR SEPARATING SOLIDS FROM LIQUID 5 Sheets-Sheet 5 OriginalFiled Feb. 28, 1962 Fig.3

. INVENTORS.

l 48 FREDERICK W. KE|TH,JR. BY ANDRE C. LAVANCHY AITTORNE CENTRIFUGE FORSEPARATING SOLIDS mom LIQUID Original Filed Feb. 28, 1962 F. w. KElTH,JR, ETAL Sept 22, 1910 5 Sheets-Sheet L sol" INVENTORS FREDERICK W.KEITH, JR. BY ANDRE C, LAVANCHY ATTORNEY CENTRIFUGE FOR SEPARATINGSOLIDS FROM LIQUID Original Filed Feb. 28, 1962 P 1970 F. w. KEITH, JR.,ETAL 5 Sheets-Sheet 5 INVENTORS. FREDERICK W KEITHCJR. BY ANDRE c. LAVANHY ATTORNEY United States Patent 3,529,767 CENTRIFUGE FOR SEPARATINGSOLIDS FROM LIQUID Frederick W. Keith, Jr., Gladwyne, and Andre C.

Lavanchy, Devon, Pa., assignors, by mesne assignments, to PennwaltCorporation, a corporation of Pennsylvania Original application Feb. 28,1962, Ser. No. 176,355, now Patent No. 3,328,282, dated June 27, 1967.Divided and this application Sept. 26, 1966, Ser. No. 598,133

Int. Cl. B0411 11/00 US. Cl. 23314 9 Claims ABSTRACT OF THE DISCLOSURE Acentrifuge comprising a rotor with a disc stack therein is provided witha perforated baffie means about the stack. The main feed supplies thestack with a liquid bearing solids. The solids being heavier tend toflow outwardly through the stack and through the baffie while thelighter liquid moves inwardly. A wash liquid heavier than the feed isled between the rotor wall and the baffie to entrain the solids flowingthrough the bafiles and to carry the mixture out of the centrifugeseparately from the purified feed.

This application is a division of application Ser. No. 176,355, filedFeb. 28, 1962, now US. Pat. No. 3,328,282.

This invention relates to the centrifugal separation of solids fromliquid. More specifically this invention relates to a centrifugalprocess including the compaction or concentration of solids in a mixtureof such solids and liquid and the sepaartion of the compacted solidsfrom the liquid.

The invention broadly contemplates the working or me chanical treatmentof solids in the centrifuging zone so that the solids may arrangethemselves more compactly with a consequent reduction in the liquidcontents of the solids discharge. The invention finds application inmany fields.

Since the invention was conceived and perfected in connection with thedewaxing of hydrocarbon oil and finds effective use therein, somedescription and the examples hereunder pertain to such application ofthe invention. However, it should be understood that the invention hasan application in the compaction and concentration of many solids in amixture of such solids and a liquid and of the separation of thecompacted solids from the liquid. Aside from the dewaxing of hydrocarbonoil, the invention is useful in a comparable application: theWinterizing of vegetable oil. It also finds use in the concentration ofa fiocculent sediment such as alum-loaded water treatment of solids.These uses, however, are merely illustrative of the applications of theinvention and the scope of the invention should not be limited thereby.

The prior art discloses the use of a centrifugal device to separate thehigher melting portions of a hydrocarbon oil from the portions whichmelt at lower temperatures. The Pat. 2,266,553 which issued Dec. 16,1941 on an application filed by Leo D. Jones, for instance, discloses aprocess for dewaxing hydrocarbon oil in which a mixture including oil insolvent chilled to a temperature at which a portion of the oilcrystallizes or otherwise solidifies is introduced into a centrifugingzone. The zone, which may be in the form of a centrifuge having a discstack, receives the mixture and causes the outward movement of theheavier solidified wax portions toward the periphery of the zone. Aheavy carrier liquid such as water or brine is introduced to theperiphery of the zone and serves as a means for carrying the solid waxparticles out of the bowl.

3,529,767 Patented Sept. 22, 1970 ICC The clarified oil is withdrawnfrom the inside of the disc stack at a locus about the axis of the zone.

While the apparatuses and processes of the prior art represented by theabove-mentioned patent have been successful to a large extent inseparating the wax solids from the oil, we have found that theeffectiveness of such a separation can be enhanced by the working of thesolids, e.g. wax solids, in a compaction space radially removed from theclarifying spaces, e.g. the disc stack, all within the centrifugingzone. By our process herein described, we are able to discharge from thecentrifuging zone a mass of solids which occlude and entrain far lessliquid than that discharged by the centrifuge processes of the prior artoperating under comparable multiples of the acceleration of gravity.Since a reduction in the liquid content of the solids discharge isnaturally accompanied by an increase in the clarified liquid discharge(the clarified discharge often being the more valued discharge), theeconomies of our process will be readily apparent.

We also provide for facilitation of inward movement of the liberatedliquid to the liquid discharge.

This invention embodies other novel features, details of constructionand arrangement of parts which are here inafter set forth in thespecification and claims and illustrated in the accompanying drawings,wherein:

FIG. 1 is a fragmentary sectional view of an apparatus embodying theinvention;

FIG. 1a is a portion of FIG. 1 showing modified bafile means;

FIG. 2 is a fragmentary sectional view taken on the line 22 of FIG. 1;

FIG. 2a is a fragmentary sectional view taken on the line 2a2a of FIG.1a;

FIG. 3 is a fragmentary sectional view of a modification embodying theinvention;

FIG. 4 is a fragmentary sectional view taken on the line 44 of FIG. 3;and

FIGS. 5 through 12 are sectional views in axial and indicated sectionalplanes, respectively, of four additional modifications embodying theinvention. FIGS. 5 and 6; 7 and 8; 9 and 10; and 11 and 12 pertaining tothe four embodiments respectively.

Briefly, the invention involves the introduction of a mixture includingsolids and a liquid into a zone of centrifuging comprising a clarifyingspace and a compacting space radially removed from the clarifying space.The solids after leaving the clarifying space are worked in thecompacting space. The solids are withdrawn from the zone and theclarified liquid is withdrawn separately.

In the embodiment of the invention of FIG. 1, the centrifuge rotorillustrated is of the disc type. The apparatus is broadly designated 10.It comprises a rotor 12 including a shell 14 having a central hub 16 anda top 18. The top is held down against the shell by a threaded retainingelement 20. The rotor is mounted on the power spindle 22, and receivescenter tube 24 which has its lower end disposed about the hub 16 butspaced therefrom.

The lower end of the center tube flares outwardly into a feeddistribution skirt 26 spaced from the hub and shell of the rotor. Feedopenings 27 are disposed in the skirt spaced inward from the outer edge.Surrounding the center tube 24 is a nested stack 28 of spacedfrusto-conical discs which have feed openings 29 in vertical alignmentwith the openings 27. Each disc bears radial spacers 28a which compriseaccelerator means as is conventional. Between the inner periphery of thestack 28 and the center tube 24 is a passage 30, and in alignmenttherewith is opening 32 in top 18. A dividing cone 38 which superposesthe disc stack 28, is formed with longitudinal upward extension 40, andhas its lower end extending well beyond the periphery of the disc stackcone, is spaced downward from the top 18 by a plurality of radiallydisposed circumferentially spaced wings 41. A ring dam 34 is securedover opening 32 by the threaded retaining element 36. A cover (notshown) is provided and has suitable collectors for the elfiuent.

At the lower end of the rotor about the spindle 22 is an annularinwardly facing pocket 42 partially defined by a ring element 44 securedagainst the shell. Radially disposed accelerating vanes 46 are providedin the pocket 42. From the pocket extends outward in the shell 14 thepassages 48 which communicate with an upwardly directed cone-shapedpassage defined by the shell 14 and the inward frusto-conical element50. The passage terminates in an opening adjacent the center of therotor wall. Element 50 is spaced from the shell by vanes 51. In analternate embodiment, element 50 may be replaced by a plurality of tubesextending up from passages 48.

In the embodiment of the invention disclosed in FIGS. 1 and 2,particular attention is directed to the compaction space circumposingthe clarifying spaces between the discs of the stack 28. The compactingmeans comprises the baflles 52 and 54. The inner baffle 52 is an annularelement which fits about the disc stack and is held in place between theelement 50 and the dividing cone 38. As shown, the baffle 52 comprises aseries of complementing frusto-conical ring elements arranged in zig-zagmanner to present a plurality of sets of converging surface portions. Inproduction, the bafile 52 is turned from a heavy ring of stock and is ofsufficient thickness to withstand the centrifugal force at the speedsdeveloped by the rotor. As shown in FIG. 2, the bafiie 52 is formed withperipherally spaced orifices at the juncture between adjacentfrusto-conical surfaces. The inward orifices are designated 56 and theoutward orifices are designated 58.

The baffle 54 comprises a single ring element 60 having a plurality ofspaced orifices 62. The element presents a substantially flat surfaceinward and is held in place by an annular element 64 presenting towardthe axis complementing frusto-conical surfaces arranged in zig-zagfashion. Openings 66 between the surfaces permit passage of solids.Outward circumferentially spaced legs 68 engage the wall of the rotor tohold the bafiie 54 in place. The bolts 69 secure the element 60 toelement 64. It should be noted that the openings 66 are, in theembodiments shown, inward of the outer periphery of cone 38.

In the modified form of the apparatus disclosed in FIG. la, the outerbaffle 54 is in the form of a plurality of complementing frusto-conicalring elements arranged in zig-zag fashion with orifices at innerjunctures between the rings indicated at 62' and outer orificesindicated at 62a. Suitable legs 64' may engage the wall of the rotor andextend inward to place the outer bafi le. Alternatively the outer bafiiemay be supported by a post extending outward from the inner bafile.Variations of mounting means will be obvious to one skilled in the art.

In the operation of the apparatus embodying the invention as shown inFIG. 1, the feed, which when the invention is used in dewaxing maycomprise a chilled mixture of wax solids and hydrocarbon oil which mayhave been diluted with a solvent is introduced by a conventional feedtube into the center tube 24. The mixture thence is distributedoutwardly and passes upward through the openings 27 in the skirt 26.Through the openings 29 the mixture is introduced successively into theseparating spaces between adjacent discs, and in the disc stack theliquid in the mixture is clarified; that is, the liquid only passesinward along the upper surface of the individual discs and into thespace 30 and thence over the upper edge of the longitudinal extension40.

The wax solids move outward along the underside of the individual discsfrom the openings 29. For efficiency of separation an attempt is made tokeep the so-called interface between the oil and the wax concentrate,about at the periphery of the disc stack. However, since the interfacebetween the oil and the concentrate is indistinct, no specific positionfor an interface can be defined.

The wax or other outwardly moving solids in the feed are worked in thecompacting space outward from the disc stack probably in accordance withthe theories suggested herebelow. Most of the compacted solids moveoutward through the orifices 58, 62 and 66 to the carrier liquid and aredischarged. As is conventional when carrier liquid is used, theinterface between the carrier liquid and the solids is kept close to theperiphery of the cone 38.

Oil or other inwardly moving liquid is liberated in the working of thesolids. Oil liberated between the baflies is shielded by the baffie 52from the outward movement of wax from orifices 58 and may movesubstantially unimpeded toward the openings 56. It is believed that theindividual oil particles liberated between the baffies coalesce to formglobules on the outside surfaces of the ring elements comprising baffie52, and move toward and through the orifices 56. From the orifices 56the oil moves into the disc stack for clarifying and ultimately outthrough the extension 40. Wax solids between the discs move outward intothe compacting space. The discharge of the solids as indicated iseffected by a brine or water or other immiscible fluid layer whichcomprises a carrier. The layer may be supplied by the supply tube 45which delivers the liquid into the pocket 42. The wax solids areentrained by the layer and carried through the passages between wings 41over the ring dam 34 to a suitable collector (not shown) wherein thesolids and liquids may be further separated by additional treatment suchas settling, additional centrifuging, distillation, or otherconventional means.

It should be understood that in all embodiments of the invention thedischarge of solids from the rotor can be achieved not only over adividing cone as shown in FIG. 1, but through peripheral nozzles. Suchperipheral nozzle discharge of wax solids, for instance, is disclosed inthe co-pending application Ser. No. 146,268, filed by Frederick W.Keith, Jr. in the U.S. Patent Office on Oct. 19, 1961. The apparatus ofthe invention is useful with many types of nozzle arrangements, however,and is not limited to those of this co-pending application. Anothervariation of the process involves introduction of the carrier liquidwith the feed rather than separately through passages such as 48, 50.When introduced with the feed, the carrier liquid will stratify againstthe rotor wall because of its greater density just as when introducedseparately.

In the embodiment of FIG. la, operation is presumed to be the same as inFIG. 1, with the exception that any free oil on the outside of thebafile 54 may move inward against the outside of the bafiies 54' toopenings 62 with minimal interference from outwardly moving wax.

Radial accelerators may be provided in the compaction space of theseembodiments if desired or necessary.

A modified form of the apparatus is disclosed in FIG. 3 and FIG. 4. Forsimplicity, parts of the apparatus disclosed in these figures whichcorrespond to parts of FIGS. 1 and 2 are designated by the primed formof the same reference numerals.

In the FIG. 3 embodiment, the compaction space outside of the disc stackincludes an inner bafiie 70 and an outer baffie 72. Each of thesebafiles is generally annular, and, as shown in FIG. 4 the baffle 70comprises a zig-zag configuration of vertical plates presentingperipherally arranged complementing non-radial converging surfaces.Between the juncture of two adjacent plates on the inside of the bafiie70 are orifices designated 74, while on the outside of the bafliebetween adjacent surfaces are orifices designated 76. The upper andlower ends of the baflle are suitably bevelled and engage surfaces onthe underside of dividing cone 38' and on the inside of the element 50',respectively. The outer baflie 72 as shown in FIG. 4 similarly comprisesa series of sets of zig-zag plates presenting complementing non-radialsurfaces. At the juncture between surfaces at the inside of the bafiieare openings 78, while at the juncture of surfaces at the outside of thebafiie are openings 80.

The outer baffle 72 may be supported from a series of peripherallyarranged struts 82 or posts extending inwardly from the shell wall orextending outwardly from the inner baffle 70. Any suitable means forsupporting the baffle may be devised and is within the scope of thepresent invention.

Generally the operation of the apparatus disclosed in FIGS. 3 and 4which embodies the invention is similar to the operation describedabove.

It is theorized that the embodiment of the invention as shown in FIGS. 3and 4 has the added advantage that the vertical plates of the battlesserve also as vanes to assure acceleration of the liquid in thecompaction space, and minimizes turbulence.

It can be noted from FIG. 4 that oil portions liberated from the solidsbetween the bafiles move inwardly to ward the outer surfaces of bafile70 and coalesce there to move through the orifices 74. The inwardmovement of oil is hence substantially not impeded by the outwardmovement of solids from orifices 76, an advantage which ischaracteristic of the invention. Similarly oil liberated on the outsideof baflle 72 will move inward toward and through openings 78substantially without interference from solids moving outward throughopenings 80.

In the embodiments of FIGS. 1, 2, 1a, 2a, 3 and 4 it will be noted thatsome effort has been made to avoid radial alignment of the orifices. Inother words, directly outward from an opening 58, f.i., in bafile 52 isthe surface 60. It is believed non-alignment effects better working ofthe solids and reduces the possibility of channelling.

It will be understood that the plurality of openings betweencomplementing surfaces in the baflles may instead be a continuous slotor a series of discontinuous slots. Thus, in FIG. 1, f.i., the openings56 and 58 may be continuous slots. However, better working of the solidsis achieved through individual orifices. In this connection, the sizeand number of the orifices influences the extent of the working ormechanical treatment, through optimum orifice size will differ accordingto the type of solids worked, the flow rate, and other factors. In theconditions of Example 1, orifices of about have been found optimum.

Further, in the embodiments of FIGS. 1, 2, 1a, 2a, 3 and 4 some of thebenefits of the invention can be retained by eliminating the outerbaffle means 54, 54 and 72, respectively. Similarly the baffles may berearranged and their number increased if desired and depending on thesize and configuration of the centrifuge rotor. The structures shownrepresent preferred embodiments, however, for a small rotor.

In the embodiment of the invention which is shown in FIGS. 5 and 6 thedouble primed reference numerals refer to parts with the same numeral inFIGS. 1 and 2. This embodiment comprises a rotor 12" including a discstack 28" surrounded by a compaction zone in which are positioned aplurality of circumferentially spaced vanes 100. The vanes 100 generallyextend longitudinally of the rotor, and as shown in FIG. 6 are disposedto present curved non-radical surfaces. The vanes are secured to anupper frusto-conical support 102 and a lower frustoconical support 104which are disposed between cone 38 and the element 50".

In operation, the wax solids moving outward press on the surfaces ofelements 100 and slide outwardly thereon. As the solids move otf theouter tip of the surfaces they fall out to the surface of a layer ofcarrier liquid and are discharged out of the rotor. The oil which isfreed from the solids moves inwardly along the outermost surfaces of thecompacting vanes, and then into the disc stack.

In the embodiment of the invention disclosed in FIGS. 7 and 8, thetriple-primed reference numerals refer to parts with the same numeral inFIGS. 1 and 2.

In the compacting space outside the disc stack 28" is disposed anassembly comprising support elements 160 which are circumferentiallyspaced about the axis, are

secured at their upper and lower ends to frusto-conical elements 162 and164, respectively. The elements 162 and 164 rest against the dividingcone 38" and shell 14, respectively. Mounted by the support elements arethe nested and spaced upper frusto-conical elements 166 and lowerfrusto-conical elements 168.

In operation, the solids moving outwardly from the disc stack 28 in thisembodiment press on the nonradial surfaces presented by thefrusto-conical elements 166, 168 and pass through the spaces between theelements. The oil liberated in the settling moves along the outsidesurfaces of the elements toward and into the disc stack. Alternativelythe frusto-conical elements may have orifices as in the FIGS. 9, 10embodiment to enhance the working of the solids.

In the embodiment of FIGS. 9 and 10 quadrupleprimed form of referencenumerals are used. The rotor 12"" contains the disc stack 28" withoccasional discs 28a extending out beyond the stack into the compactingzone. The extending portions present non-radial surfaces against whichoutwardly moving solids may press. The extensions, as shown in FIG. 10,are formed with spaced orifices 28b through which the solids may passfor additional working and compaction.

As pointed out above, this invention broadly contemplates the working ofoutwardly moving solids in a compacting space within a centrifugingzone. This working may be accomplished by the apparatuses describedabove as well as reasonable variations thereof. Our experimental Workbears this out as indicated in the examples. The detailed action of thesolids in the compacting zones of the various embodiments is not known.However, it is believed that at least three actions of differentcharacter transpire within the compacting spaces disclosed.

The first action is the pressing of the solids against a non-radialsurface as they meet the surface in their outward movement toward theperiphery of the rotor. Such pressing may include a mere contact uponwhich delicately associated solids may compact. The non-radial surfacesmay be disposed at any angle to a radius, but it is assumed that forthis type of action, the most thorough pressing will be done against asurface perpendicular to a radius. Pressing of the solids against anon-radial surface is common to all of the embodiments disclosed herein.Liquid liberated from the pressing moves inward toward the axis.

A second action of the solids is effected by their passage through anorifice. As it passes through an orifice each agglomerate of solids isworked against its neighbor. This working is accomplished by changes inrelative motion of the stream filaments in the flow pattern and thevelocity pattern particularly as the solids approach the orifice orother structure modifying the flow pattern. In such working, the solidsor agglomerates are rearranged so that they approach each other moreclosely. This rearrangement may or may not be accompanied by a physicalbreaking of projections on individual solids or of punctures betweensolids in agglomerates so that the solids fit together closer. The exactaction about the orifice de pends, of course, on the velocity and thetype of fluid passing through. As a higher degree of compaction isestablished liquid which filled the interstices between the solidparticles and/ or solid agglomerates is proportionately displaced andliberated from the agglomerates or solids bed. On the outside of theorifice the solids retain their rearrangement and move outwardly. Theliberated liquid moves inward, may coalesce on the outer surfaces of thebafiles and moves with substantially no interference from the outwardlymoving solids. This action is present at least in the embodiments ofFIGS. 1, 1a, 2, 2a, 3, 4, 9 and 10.

A third action on the solids is quite comparable to the second and isbelieved to be effected by the passage of solids between surfacesconverging outward from the axis. This action is a working of the solidsagainst their neighbors as they move toward the point of convergence. Itmust be assumed that the solids must work relatively to each other insuch movement, and in so doing they rearrange themselves more compactly.This rearrangement may or may not be accompanied by a breakotf of projections of the individual solids, or, indeed, of junctures betweenadjacent solids. Liquid liberated moves inward. The movement of thesolids along converging surfaces will be present at least in theembodiments of FIGS. 1, 1a, 2, 2a, 3 and 4.

It must be reiterated that the exact action of the solids in the variouscompaction Zones is not known. The above theorizing is intended not inany way to limit the scope of the invention but merely to assist thoseskilled in the art to better understand the invention.

In FIGS. 11 and 12 the reference numerals of FIGS. 1 and 2 augmented by100 are again used to designate corresponding parts. The embodimentshown herein is designed for use with mixtures in which the compatiblesolids are lighter than a primary liquid in the mixture.

As shown, the disc elements 128 are truncated inwardly to provide acompaction space inside the stack. In the compaction space is the outerzig-zag battle 153 and the inner batfie 155. These annular battles areclamped in place between the dividing cone 138 and skirt 126. Theopenings similar to the openings in the bafties of FIGS. 1 and 2 are notaligned. A carrier liquid feed collar 157 is mounted spaced about centertube 124 if desired or necessary.

In operation, the mixture is fed through center tube 124 as withprevious embodiments. The light solids move inwardly through the discstack and through the battles. The heavy liquid moves outward and may bedischarged with assist from a heavy carrier liquid if desired ornecessary, operating in earlier disclosed embodiments, over dam 134.Alternatively the heavy liquid may be discharged through peripheralnozzles, if the nature of the liquid permits. To assist discharge oflight solids, a liquid carrier may be spilt down collar 157 to ride thesolids out extension 140.

The action of the baffles 153, 155 in the compacting space on the lightsolids has result comparable to that of the action of the battles in theearlier disclosed embodiments; namely the compaction and concentrationof the solids. Variations of the structure of the battles of the FIG. 11embodiment are within the scope of the invention. The baffle strutcuresof the preceding embodiments suggest some variations.

Some lighter solids which may be compacted by the embodiments similar tothat of FIGS. 11 and 12 are various flocculent solids lighter than theliquid in which they are mixed. It is, for instance, possible to dewaxpetroleum stocks with such apparatus if the oil-solvent liquid isheavier than the wax solids, as would be the case for instance if thesolvent were one of the chlorinated hydrocarbons.

The theory set forth above in connection with the FIGS. 1-10 embodimentsapplies equally to the FIGS. 1l12 embodiment, except that the liberationand action occur as the solids move inwardly.

The following examples, meant not by way of limitation but as anillustration, are representative of operation of the apparatus disclosedin FIGS. 1 and 2.

EXAMPLE 1 A rotor roughly inches in diameter as disclosed in FIG. 1having about fifty spaced discs and batlies as shown was rotated at aspeed of about 4500 rpm. A petroleum fraction having a pour point ofapproximately 40 F., diluted with methylethyl ketone, was fed at therate of 1 gallon per minute at 5 F. Its wax content was solvent was 6%.A supply of about /2 gallon per minute of brine through the line 45carried wax solids with the brine over the ring dam 34. Wax at 41% oilafter decanting the brine and stripping off the solvent was produced.

8 EXAMPLE 2 The apparatus of Example 1 was operated at the same speedand under the same conditions, including feed rate. However, in thisoperation the baflles 52 and 54 were removed. The wax discharged in thebrine over the ring dam 34 analyzed at 48% oil after decanting the brineand stripping off the solvent.

In all embodiments the liberation of oil from the interstices betweenthe wax solids as well as the entrainment of the solids themselves bythe carrier layer flow may be facilitated by the addition of surfaceactive agents, preferably of the ionic type, such as the commercialproducts known in the trade as Tergitol or the various organicphosphorus compounds such as sodium didecyl phosphate as discussed inthe US. Pat. 2,793,169, which issued May 21, 1957. Such agents increasethe tendency of the carrier liquid to wet the wax solids, and replacethe oil on the surfaces thereof.

It should be understood that some solids with which the invention isuseful for compacting may be discharged from the rotor without the aidof a carrier layer. In such case a simple nozzle or dividing conearrangement may be utilized.

Mention is made again that this invention has a wide range of uses andis not limited to the dewaxing of hydrocarbon oil and other applicationsmentioned.

Additionally the process of the invention may be practiced in a numberof different apparatuses aside from those disclosed herein. In thisconnection, reasonable variations of the apparatuses disclosed may bemade. For instance in applications in which large clarification spacesare not felt to be required, the diameter of these spaces may be reducedand a larger portion of the rotor may be devoted to the working of thesolids. Discs the diameter of the rotor, for instance, are feasible.

Another variation may substitute as the compaction means, e.g. thebaffies 52 and 54 of FIGS. 1 and 2, loose solid elements held in placein the rotor by centrifugal force. The elements may take the form ofdistillation tower packing such as small cylinders of suitable size ofceramic material, plastic, metal, especially stainless steel; berlsaddles; rasching rings; or other commercially available packings ofsimilar varieties. In operation such loose solid elements will presentnon-radial surfaces against which the solids in the mixture may compactand irregularly restricted flow paths which serve to work the solids asdo the orifices in the perforated bafiles discussed above.

It is thus to be understood that the above particular desorption is byWay of illustration and not of limitation, and that changes, omissions,additions, substitutions and/ or other modifications may be made withoutdeparting from the spirit of the invention. Accordingly it is intendedthat the patent shall cover, by suitable expression in the claims, thevarious features of patentable novelty that reside in the invention.

\Ve claim:

1. A centrifuge comprising a rotor, a disc stack within said rotor,bafile means surrounding the disc stack, and spaced inward from the Wallof the rotor, and presenting non-radial surface portions, the baffiemeans having openings between adjacent surface portions, feed means forfeeding mixture into the rotor, and discharge means for separatelydischarging components of the mixture from the rotor, said battle meanscomprising inner and outer baffle plates each having outwardlyconverging surface portions with openings therebetween.

2. A centrifuge comprising a rotor, a disc stack within the rotor,baffle means disposed inside of the disc stack and presenting non-radialsurface portions, feed means for feeding mixture into the rotor, anddischarge means for withdrawing a light compacted solid component from alocus inward of the baffle means.

3. A centrifuge as described in claim 2 wherein the battle meanscomprises a series of frusto-conical rings arranged in zig-zag fashionto present surfaces converging toward radii of the rotor, and whereinadjacent rings have openings therebetween.

4. A centrifuge for compacting the solids in a mixture of such solidsanda liquid and for separating the liquid in clarified condition fromthe solids, comprising: a rotor having an outer wall formed about anaxis and mounted for rotation on said axis, a stack of frusto-conicaldiscs within a portion of said rotor and defining frusto-conicalclarifying spaces therein, baflle means annularly disposed about saidaxis and provided with non-radial surface portions and restrictedpassages between adjacent surface portions defining an annularcompacting space adjacent said clarifying spaces, said bafile meansbeing spaced inwardly from the rotor wall, a passageway for carrierliquid extending along said rotor wall, said passageway communicatingwith said clarifying spaces andsaid compacting space and being radiallydisplaced therefrom, means for discharging clarified liquid from theclarifying spaces in said rotor, means for conducting said mixture intosaid clarifying spaces for flow of clarified liquid along said discstack toward said discharging means and for flow of solids withentrained liquid into said compacting space, the restricted passages insaid bafile means conducting the solids toward the passageway forcarrier liquid and the non-radial surface portions of said baffie atleast partly defining means for conducting the liquid separated from thesolids in the compacting space back toward the clarifying spaces fordischarge with the clarified liquid, and means for separatelydischarging the carrier liquid with the separated solids carried therebyfrom the rotor.

5. The centrifuge of claim 4 wherein the surface portions are vertical.

6. The centrifuge of claim 4 wherein the surface portions arefrusto-conical and coaxial with the disc stack.

7. The centrifuge of claim 4 wherein the disc stack is superposed by adividing cone the periphery of which extends to a radius greater thanthat of the bafile means.

8. The centrifuge of claim 4 including separate means to supply a liquiddirectly to the inner periphery of the rotor.

9. The centrifuge of claim 1 wherein the bafile means comprises anoutward extension of one of the discs, the extension having an openingtherein.

References Cited UNITED STATES PATENTS 1,014,849 1/ 1912 Richardson 23321,168,454 1/1916 Anderson 23 335 1,482,418 2/ 1924 Unger 23329 2,261,72411/1941 Holm 208--31 2,313,540 3/1943 Hall 23314 2,578,485 12/ 1 Nyrop23346 X-R 2,599,619 6/1952 Eckers 23315 2,724,549 11/1955 Brown 233--23,117,928 1/ 1964 Thylefors 233-29 XR FOREIGN PATENTS 51,514 4/ 1890Germany. 1,099,465 2/1961 Germany.

408,926 7/ 1932 Great Britain. 856,183 12/ 1960 Great Britain.

HENRY T. KLINKSIEK, Primary Examiner US. 01. X.R. 233-2, 29, 47

